Powdery Mildew (IMAGE) University of Missouri-Columbia Caption This shows powdery mildew on a cabernet sauvignon grapevine leaf. Credit USDA grape genetics publications and research. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.